Quality check

Quality check and calculation of drought indices for the hydrological stations from the ADO project

Summary of Station ADO_DSC_SI03_0033 in Slovenia in HE Dravograd.

Metadata information

This dataset is aggregate at daily resolution with units in m3/s:

country region location_site lat lon start_date end_date waterourse height_masl height_dem catchm_area source_id note_influence
Slovenia Vzhodna Slovenija HE Dravograd 46.586959 15.023492 1965-01-01 2019-12-31 Drava None 334.9377 None None None

Primary statistics

Basic description and statistics of the dataset:

ADO_DSC_SI03_0033
count 20085.000
mean 260.717
std 139.993
min 57.852
25% 159.531
50% 227.999
75% 322.000
max 1799.000

Missing values

Description of periods with missing values in the dataset

Start date End date Missing values
1952-10-01 1964-12-31 4475
1984-12-31 1984-12-31 1
1988-12-31 1988-12-31 1
2004-12-31 2004-12-31 1

Maximum threshold

Dates exceeding the maximun threshold in the dataset defined as eleven times the standard deviation

date ADO_DSC_SI03_0033
1966-08-19 1789.0
1966-08-20 1799.0

Minimum values

Top Ten lowest values in the historical period

date ADO_DSC_SI03_0033
2002-01-01 57.85
2002-04-01 58.16
2002-03-31 60.38
2019-01-27 64.65
2006-12-06 64.93
2001-12-30 66.29
2002-01-24 69.17
1996-03-03 69.84
2003-04-12 70.09
2008-02-17 70.71

Maximum values

Top ten highest values in the historical period

date ADO_DSC_SI03_0033
1966-08-20 1799.00
1966-08-19 1789.00
1966-11-06 1670.00
1965-09-04 1669.00
1965-09-05 1632.00
1966-11-05 1584.00
2012-11-05 1416.98
1965-09-03 1411.00
1966-08-18 1399.00
1998-10-08 1375.82

Discharge time series

Monthly discharge for the station ADO_DSC_SI03_0033

Hydrological regime

Hydrologic regime means the entire state of the streamflow in a given area over the course of a year. It is a function of the climate. The factors affecting the river regime include precipitation, temperature, evapotranspiration and the physical properties of the drainage basin. The following graphs describes the discharge regime for the multi-year period of records at different temporal scales. The shaded area represents the quantile 5 and 95.

- Daily scale
- Monthly scale

Flow duration curve and Q95 Index

Q95 is also called Q347. Is one of the low flow duration indices, denotes the discharge of the watercourse which is at least reached or exceeded for 95% of the time, that is on 347 days in an average year. For this station the Q95 value is 107.0 m3/s.

Streamflow Drought Index (SDI)

This index has been developed by Nalbantis and Tsakiris. Follow the basic concept of the Standardized Precipitation Index (SPI). The SDI can be computed at different time scales, where monthly streamflow is aggregated over a period (1-month, 3-months, 6-months, 9-months, 12-months).

- SDI-1 index

The 1-month SDI is a short term index. Compares the streamflow of each month with the average streamflow over the historical record of the same month.

- SDI-3 index

The 3-month SDI index provides a comparison of the streamflow over a specific 3-month period with the mean streamflow from the same 3-month period for all the years included in the historical record. A 3-month SDI gives a short and medium-term condition, and reflects a seasonal estimation of the streamflow condition. In this analysis is used the last quarter of the year to indicate the begining of the hydrological year:

- SDI-6 Index

The 6-month SDI provides a comparison of the streamflow over 6-month period with the average streamflow from the same period over the historical record. This index indicates a medium-term condition in streamflow. In this case it is used the first six months of the hydrological year.

- SDI-12 ndex

The 12-month SDI provides an indication for the 12 consecutive months of the hydrological year with the same 12 consecutive months during all the years of the historical record. At this time scale the index reflects long-term streamflow patterns. Since, this time scale is the cumulative result of shorter periods. The longer SDI values tend to zero unless a specific trend is taking place. The Hydrological year goes from October to September.

Discharge distribution

Statistical distribution fitting

In order to calculate the the Standardized Streamflow Index (SSI/SSFI) the following distributions are evaluated and their respected parameters are reported below. For the charts below it is considered the General Extreme Value (GEV) for the fitting in order to compare all the stations with the same approach. For more information on the considered distribution see index factsheet.

sumsquare_error Akaike information criterion Bayesian information criterion Kullback-Leibler divergence
gamma 0.000036 1459.806343 -11011.653081 inf
pearson3 0.000036 1459.806286 -11011.653063 inf
lognorm 0.000043 1457.119164 -10897.763904 inf
genextreme 0.000048 1463.607651 -10824.272050 inf
genpareto 0.000082 1442.851792 -10471.214113 inf

Kolmogorov Smirnov Test

This test is used to decide if a sample comes from a population with a specific distribution, in this case if the fitted data comes from the General Extreme Value distribution. KS test returns two parameters D statistic and p-value, which D-statisctics is the absolute maximum distance between the two CDFs of the two samples, the closer to 0 the more likely is that the two samples belong to the same distribution. P-value corresponds to the probability value, in which the null hypothesis is rejected if the p-value is less than the significance level, in this case 0.05.

General extreme value D-statistic P-value
Kolmogorov-Smirnov test 0.044325 0.145075

Standardized Streamflow Index (SSI/SSFI)

It follows also the theoretical concept of the standardized precipitation index (SPI). Can be computed at different time scales, where monthly streamfloe is aggregated over a period of time, as the same as SDI. This index allows accurate spatial and temporal comparisons of the hydrological conditions of a stream (Telesca, 2011). This index compares normal streamflow for a specific rolling windows sum. For more information see index factsheet.

- SSI-1 Index

The 1-month SSI is a short term index. It compares normal streamflow for the month with the average streamflow over the historical data of the same month. The long-term streamflow record is fitted to a probability distribution. So the median SDI is zero. That means positive SDI values indicate greater than the median streamflow, and negative values indicate less than the median streamflow.

- SSI-3 Index

The 3-month is the time step for the rolling window sum.

- SSI-6 Index

The 6-month is the time step for the rolling window sum.

- SSI-12 Index

The 12-month is the time step for the rolling window sum.